A Horizontal Line
The basic divider line looks like a grey horizontal line that takes up the entire page (or table cell, div blog, whatever).
There's no need for a closing tag, to make a horizontal line on your page, you just use <hr>. But what fun is a icky grey line that doesn't match the rest of your page?
Changing Attributes
You can easily adjust the height and width of a divider, along with the background color. Here is an example of a divider I just thought up 2 seconds ago:
Of course, you can change the size of it and the color to whatever you want, but below is just the code I hate for my exmaple divider.
Where width is how wide you want it to be in pixels, size is how tall you want the divider (ie. how thick you want it) and color is what color you want it (in names or hec color codes).
It is better to make changes with a stylesheet because you can do more with CSS a this stage than HTML.
Vertical Line
I'm not sure why you'd want a vertical line because you can't write words on either side and it just seems odd, but for people who want a vertical line, you can do so with the following code:
Which would then give me something that looked like this:
And you can change the size and color of it as always.